Flame-retarded adhesive composition

Abstract

A hot-melt adhesive composition based on ethylene/vinyl actetate copolymer comprising not more than 35% (preferably not more than 30%, more preferably not more than 25%) by weight, based on the whole composition, of halogen-free char-forming flame-retardant additive(s) in an amount at least sufficient to prevent flaming drips generated on burning of the adhesive from igniting the underlying absorbent cotton according to the 20 mm Vertical Burn Test of Underwriters Laboratories Test Method UL-94 (1993), V-1, preferably V-0. Preferred halogen-free flame-retardant additives include ammonium phosphates, melamine cyanurate, zinc borate, and especially red phosphorus.

I claim: 
     
       1. A hot-melt adhesive composition based on ethylene/vinyl acetate copolymer, which copolymer has (a) at least 16% by weight vinyl acetate content and (b) a Melt Flow Index of at least 100 g/10 minutes at 190° C. using a 2.16 kg. weight according to ASTM D138 (1979), the adhesive composition comprising not more than 35% by weight, based on the whole composition, of halogen-free char-forming flame-retardant additive(s) in an amount at least sufficient to prevent flaming drips generated on burning of the adhesive from igniting the underlying absorbent cotton according to the 20 mm Vertical Burn Test of Underwriters Laboratories Test Method UL-94 (1993), V-1, while leaving the adhesive composition with a Melt Flow Index (tested as above) of at least 50 g/10 minutes, and wherein the flame-retardant additive is phosphorous-containing and comprises one of (a) ammonium phosphate, and (b) an organic amine phosphate. 
     
     
       2. A composition according to claim 1, which is substantially entirely halogen-free. 
     
     
       3. A composition according to claim 1, which is substantially free of finely-divided silica or alumina fillers. 
     
     
       4. A composition according to claim 1 having a Melt Flow Index, eexpressed in g/10 minutes, measured according to ASTM D138 (1979) at 190° C. using a 2.16 kg weight, of at least 50. 
     
     
       5. A composition according to claim 1, wherein the base polymer has a Melt Flow Index, expressed in g/10 minutes. measured according to ASTM D138 (1979) at 190° C. using a 2.16 kg weight, of at least 100. 
     
     
       6. A composition according to claim 1, comprising at least 20% by weight of the ammonium phosphate (a) or the organic amine phosphate(b). 
     
     
       7. A composition according to claim 1, comprising a synergist for the ammonium phosphate (a). 
     
     
       8. A composition according to claim 7, comprising at least 15% by weight of the combined ammonium phosphate and synergist. 
     
     
       9. A composition according to claim 1 wherein the flame-retardant additive comprises red phosphorus. 
     
     
       10. A hot-melt adhesive composition based on ethylene/vinyl acetate copolymer, which copolymer has (a) at least 16% by weight vinyl acetate content and (b) a Melt Flow Index of at least 100 g/10 minutes at 190° C. using a 2.16 kg. weight according to ASTM D138 (1979), the adhesive composition comprising not more than 35% by weight, based on the whole composition, of halogen-free char-forming flame-retardant additive(s) in an amount at least sufficient to prevent flaming drips generated on burning of the adhesive from igniting the underlying absorbent cotton according to the 20 mm Vertical Burn Test of Underwriters Laboratories Test Method UL-94 (1993), V-1, while leaving the adhesive composition with a Melt Flow Index (tested as above) of at least 50 g/10 minutes, wherein said flame-retardant additive comprises at least 1% by weight of red phosphorus. 
     
     
       11. A composition according to claim 10, comprising not more than 10% by weight of the red phosphorus. 
     
     
       12. A hot-melt adhesive composition based on ethylene/vinyl acetate copolymer, which copolymer has (a) at least 16% by weight vinyl acetate content and (b) a Melt Flow Index of at least 100 g/10 minutes at 190° C. using a 2.16 kg. weight according to ASTM D138 (1979), the adhesive composition comprising not more than 35% by weight, based on the whole composition, of halogen-free char-forming flame-retardant additive(s) comprising melamine cyanurate in an amount at least sufficient to prevent flaming drips generated on burning of the adhesive from igniting the underlying absorbent cotton according to the 20 mm Vertical Burn Test of Underwriters Laboratories Test Method UL-94 (1993), V-1, while leaving the adhesive composition with a Melt Flow Index (tested as above) of at least 50 g/10 minutes. 
     
     
       13. A composition according to claim 12, comprising at least 10% by weight of the melamine cyanurate. 
     
     
       14. A hot-melt adhesive composition based on ethylene/vinyl acetate copolymer, which copolymer has (a) at least 16% by weight vinyl acetate content and (b) a Melt Flow Index of at least 100 g/10 minutes at 190° C. using a 2.16 kg. weight according to ASTM D138 (1979), the adhesive composition comprising not more than 35% by weight, based on the whole composition, of halogen-free char-forming flame-retardant additive(s) comprising zinc borate in an amount at least sufficient to prevent flaming drips generated on burning of the adhesive from igniting the underlying absorbent cotton according to the 20 mm Vertical Burn Test of Underwriters Laboratories Test Method UL-94 (1993), V-1, while leaving the adhesive composition with a Melt Flow Index (tested as above) of at least 50 g/10 minutes. 
     
     
       15. A composition according to claim 14, comprising at least 10% by weight of the zinc borate. 
     
     
       16. A composition according to claim 1, which is a hot melt adhesive based on ethylene/vinyl acetate copolymer, which copolymer comprises at least 20%, by weight of the vinyl acetate. 
     
     
       17. A composition according to claim 1 carried on a dimensionally heat-recoverable article, the amount of flame-retardant additive(s) being less than that which prevents the composition from softening and/or flowing to effect sealing under conditions to which it is subjected during normal heat recovery of the said article in use. 
     
     
       18. A wire having a composition according to claim 17 in contact therewith and having the said heat-recoverable article heat recovered around it. 
     
     
       19. A cable joint having a composition carried on a dimensionally heat-recoverable article and comprising a hot-melt adhesive composition based on ethylene/vinyl acetate copolymer, which copolymer has (a) at least 16% by weight vinyl acetate content and (b) a Melt Flow Index of at least 100 g/10 minutes at 190° C. using a 2.16 kg. weight according to ASTM D138 (1979), the adhesive composition comprising not more than 35% by weight, based on the whole composition, of halogen-free char-forming flame-retardant additive(s) in an amount at least sufficient to prevent flaming drips generated on burning of the adhesive from igniting the underlying absorbent cotton according to the 20 mm Vertical Burn Test of Underwriters Laboratories Test Method UL-94 (1993), V-1, while leaving the adhesive composition with a Melt Flow Index (tested as above) of at least 50 g/10 minutes and being less than that which prevents the composition from softening and/or flowing to effect sealing under conditions to which it is subjected during normal heat recovery of the said article in use, said cable joint being in contact with said composition and having the said heat-recoverable article heat recovered around it. 
     
     
       20. A harness having a composition carried on a dimensionally heat-recoverable article and comprising a hot-melt adhesive composition based on ethylene/vinyl acetate copolymer, which copolymer has (a) at least 16% by weight vinyl acetate content and (b) a Melt Flow Index of at least 100 g/10 minutes at 190° C. using a 2.16 kg. weight according to ASTM D138 (1979), the adhesive composition comprising not more than 35% by weight, based on the whole composition, of halogen-free char-forming flame-retardant additive(s) in an amount at least sufficient to prevent flaming drips generated on burning of the adhesive from igniting the underlying absorbent cotton according to the 20 mm Vertical Burn Test of Underwriters Laboratories Test Method UL-94 (1993), V-1, while leaving the adhesive composition with a Melt Flow Index (tested as above) of at least 50 g/10 minutes and being less than that which prevents the composition from softening and/or flowing to effect sealing under conditions to which it is subjected during normal heat recovery of the said article in use, said harness being in contact with said composition and having the said heat-recoverable article heat recovered around it. 
     
     
       21. A composition according to claim 1 wherein there is only one flame-retardant additive present.